Mail inserters have played a significant role among the labor saving devices available to businesses, which are engaged in the daily mailing of large numbers of pieces. Among the advantages of inserter usage has been the reduction in personnel required to process large quantities of outgoing mail. In a typical mail inserter, a plurality of enclosure feeders are used to release a plurality of enclosure materials or documents into the chassis of the inserter. The released documents are pushed downstream and collated into a stack. The stack is then inserted into an envelope in an insertion station. Inserters and enclosure feeders are known in the art. For example, Foster et al. (U.S. Pat. No. 4,418,515) discloses a mail inserter having a plurality of sloped trays, each of which carries a stack of documents, wherein one or more feed rollers are used to pick up a sheet of document at a time and release it into a chassis. Godlewski (U.S. Pat. No. 4,715,593) discloses a bottom stack feeder wherein a feeding mechanism having a plurality of feed rollers and pullout roller is used to pull out a sheet of stock items from the bottom of the stack in the feeding process.
The released documents are released from different feeders in the collation process. It is important that the released documents are fed evenly in that each document should be released onto the chassis with the leading edge substantially perpendicular to the releasing direction. However, the friction characteristics of the documents and the feeding mechanism sometimes render it difficult to achieve an even feeding. In an uneven feeding, the feed is skewed such that one side of the leading edge of the released document may move faster than the other side of the leading edge. Uneven feed may cause machine errors.
Thus, it is advantageous and desirable to provide a method and apparatus for controlling feeding of documents or enclosures in order to correct for the uneven feeding.